During a PCR (Polymerase Chain Reaction), the sample to be investigated is subjected to a cyclical temperature treatment in which the DNA fragments are essentially duplicated with the aid of a primer pair and a polymerase. For this kind of analyses, there are nowadays processes available in which the PCR is carried out on a microchip which has an array of microspots which form “gel pads” (WO 01/34842 A2). In order to enable hybridizations within the microspots to be detected by fluorescence spectroscopy, the known processes involve adding a labeled primer to the analyte solution.
Methods for amplifying and detecting nucleic acids are known from the prior art. Here, gel pads may form separate microspots as hydrophilic reaction layers on a microarray, said gel pads containing oligonucleotides which can hybridize with target nucleic acids to be identified. Furthermore, the printed publication “Nucleic Acids Res.” (1999) 27 (18) e19, pages 1 to 6, discloses carrying out amplification reactions in gel pads on a microarray and detection reactions by way of single base elongation. In this connection, mention should further be made of DE 196 10 115 C2 which discloses an array having a microelectrode arrangement and of WO 01/42508 A2 which discloses gel pads with immobilized probes in contact with microelectrodes.
Finally, WO 99/36576 A1 involves the use of gel pads in an array and also methods and systems for their preparation, it being intended to prepare “intelligent gels” as reaction layers.